Roller clutch reversing mechanism

ABSTRACT

This application relates generally to a reversible force or torque transfer device. This device may be used in many different applications. The example used for the illustrative purposes of this patent is a wrench. The present invention devises a reverse mechanism that can resist any amount (up to the shear strength of the material) of randomly generated forces that may cause this effect.

FIELD OF THE INVENTION

This application relates generally to a reversible force or torquetransfer device. This device may be used in many different applications.The example used for the illustrative purposes of this patent is awrench.

BACKGROUND

Extensive prior art exists in the field of indexing wrenches that areused to tighten or loosen fasteners. For the class of wrenches thatemploy roller clutches to transfer torque from the wrench to thefastener, it is possible that the geometric configuration of the wrenchmay result in forces that cause the reversing mechanism to beback-driven. If these forces are large enough, the reverse mechanism mayenter a neutral position or cause the wrench to change direction.

The present invention devises a reverse mechanism that can resist anyamount (up to the shear strength of the material) of randomly generatedforces that may cause this effect.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a wrench that includes the reversemechanism device sub-assembly in accordance with the teachings of thisdisclosure.

FIG. 2 is an exploded view of the reverse mechanism in accordance withthe teachings of this disclosure.

FIG. 3 is a close-up perspective view of the major parts that comprisethe reverse mechanism device.

FIG. 4 is a close up view of two of the reverse mechanism's major partsillustrating several important geometric features.

FIG. 5 is a close up view of one of the reverse mechanism's major partsillustrating important geometric features.

FIG. 6 is a close-up sectional view of the reaction forces present inreverse mechanism in accordance with the teachings of this disclosure.

FIGS. 7 a, 7 b, and 7 c is a series of sectional views of the reverse asit moves from a forward (clockwise) to a reverse setting and then backto the forward setting, in accordance with the teachings of thisdisclosure.

FIG. 8 presents a series of sectional views of the reverse as it movesfrom a forward (clockwise) to a reverse setting, in accordance with theteachings of this disclosure.

FIGS. 9 a and 9 b present a series of views of the reverse mechanismdetent hammer as it moves from a forward (clockwise) to a reversesetting, in accordance with the teachings of this disclosure.

DETAILED DESCRIPTION

Referring to FIG. 1, three perspective views of a wrench 200 thatcontains the reverse mechanism device 100 are shown. The moment arrows101 and 102 illustrate the forces that must be applied to the thumblever 112 and spindle tang 141 when operating the reverse mechanism 100.In this case, applying the moment arrows 101 and 102 place the reversemechanism 100 in the forward setting. The forward setting results in thewrench transferring torque in the clockwise direction (the wrench 200 isable to tighten a right-hand threaded fastener) when viewed from theback of the wrench (thumb lever 112 faces the user when held in thisorientation).

The reverse mechanism 100 is shown in an exploded state in FIG. 2. Thisfigure provides additional perspective on how the parts of reversingmechanism 100 may assemble. For the purpose of this disclosure, FIG. 2allows the listing of parts with surfaces that develop reactionaryforces when reverse mechanism 100 is operated. These are: rigid spindle140, rigid rollers 150, rigid housing 160, rigid detent slider 130,rigid cage 120, rigid detent hammer 190, and rigid thumb lever 110.

Sub-assembly 300 in FIG. 3 shows several parts of reverse mechanism 100assembled in a perspective view. Sub-assembly 400 is a sectional view ofthe same parts. The sectional cut was applied so that the critical partsurfaces that develop reactionary forces are visible. In sub-assembly400 thumb lever 110 has been assembled to the cage 120 and held in placewith the retaining clip 123 (clip 123 is hidden behind sliding detent130). Rigid detent hammer 190 and flexible spring 195 are assembled indetent guide channel 111 and are also hidden by cage 120. Rigid detentslider 130 is inserted into the cage channel 121 such that detent sliderhole 131 fits over the rigid triangular boss 114 of rigid thumb lever110. Spindle 140 slides onto cage 120, with detent grooves 141 or 142mating with either sliding hammer tooth 135 or 136. The geometry of thispreferred embodiment does not require the spindle detent grooves to bemated with a particular detent tooth. This is by design. The detentgrooves 141 and 142 are 180 degrees apart. The detent hammer teeth 135and 136 are symmetrically offset from 180 degrees by the tooth angle 132(FIG. 4). In a less desirable embodiment, this relationship could bereversed and the detent teeth 135 and 136 could be 180 degrees apart andthe detent grooves 141 and 142 could be symmetrically less than 180degrees apart.

The geometry of the parts comprising device 100 are designed to achievenear tangency of the rollers 150 with three enclosing contact surfaces:pillar surface 126, rigid housing surface 162, and spindle ramp surface143 b (FIG. 4). When the reverse mechanism 100 moves from forward toreverse or the opposite, pillar width 124 and sliding detent tooth angle132 must be carefully designed to create the near tangent conditionsshown in FIG. 4. If pillar width 124 is increased, then tooth angle 132must decrease. If the pillar width 124 decreases, then tooth angle 132must increase. If tooth angle 132 increases too much, detent hammerteeth 135 and 136 are difficult to design without interference with thespindle surface 144 and the mechanism fails to work. Also, if pillarwidth 124 becomes too large, it is possible that it may interfere withroller 150 when large torque is transferred through device 100 and theroller 150 travels high up the ramp 143 b.

By design, triangular boss 114 fits smoothly with sliding hammer surface137 (see, for example, FIGS. 3,4,5,6, and 7 a-c). The shape of surface137 is determined by the equation of line 134. Equation of line 134 inCartesian coordinates, is:x=r*sin(gamma),y=−r*cos(gamma)+[Total detent slidemovement]/(2*sin((180−beta)/2))*sin((180−beta)/2−gamma),  Equation 1000:

-   -   where:        -   position x=0, y=0 is at the center of the part 130            (intersection of axis 138 a and 138 b, FIG. 4),        -   r=radius 118−radius 113 (FIG. 5),        -   Total detent slide movement=2*distance 139 a (FIG. 4),        -   Beta=angle 119 (FIG. 5),        -   gamma=from 0 degrees through (angle 125 (FIG. 3)−2*(angle            133)(FIG. 4)).

Surface 137 is symmetric about axis 138 a and is the preferred shape forhole 131. It provides for smooth motion of the sliding hammer 130 whenthumb lever 110 is rotated. The shape of surface 137 also maintains anear tangency with both radiuses 116 and 117 (radii 116 and 117 areequal) with surface 137 simultaneously. The triangular boss angle 119(FIG. 5) affects the shape of hole 131 by way of equation 1000. Thetriangular boss corner radius 113 affects the shape of hole 131.Distance 139 b (FIG. 4) is equal to radius 113. The distance thatsliding detent hammer must slide forward in order to engage a detentgroove 141 or 142 (distance 139 a, FIG. 4) is also a variable in theequation of line 134. Axis 139 c is the location of thumb lever 110center of rotation relative to sliding detent 130 when detent 135 isfully seated.

Seat angle 133 (FIG. 4) and triangular boss angle 119 (FIG. 5) determineangular distance 128 (FIG. 3), the angular distance between the centersof detent cups 121 and 122. Angle 128 is:Angle 128=angle 119+2*(seat angle 133).  Equation 2000Seat angle 133 affects the shape of hole 131 so that any reactionaryforces cannot back-drive the triangular boss 114.

FIG. 5, with several perspective views of thumb lever 110, alsoillustrates in detail the preferred arrangement of the detent hammer 190and thumb lever 110. The detent hammer channel 111 is aligned with thethumb lever protrusion 112. This allows the thickness 113 of the thumblever to be relatively small compared to the depth of the detent channel111. The depth of detent channel 111 is configured so that a portion ofthe detent hammer 190 will protrude from the channel 111. The height ofthis protrusion is slightly smaller than the depth of detent guideprofile 123. The portion of detent hammer 190 that protrudes from thesurface of thumb lever 110 is inserted into the pocket that is formed bydetent guide profile 123 (FIG. 3) when the thumb lever 110 is assembledto the cage 120.

Referring to FIG. 6, arrow 200 represent a randomly applied moment tospindle 140 relative to the cage part 120. Moments such as moment 200can develop due to friction between parts and from moments appliedperpendicular to the axis of rotation of device 100. If sliding detent130 and roller bearings 150 were temporarily removed from device 100,spindle 140 could rotate freely about the cage part 120 at surface 230.But, with the sliding detent 130 installed in reverse mechanism 100 andheld in place by thumb lever triangular boss 114, spindle 140 cannotrotate freely and any moments that develop result in reactionary forces205 or 210 depending on the direction of the moment. If triangular boss114 was temporarily removed from the device 100, reactionary forces 205or 210 would cause sliding detent 130 to slide in channel 121 such thatdetent tooth 135 or 136 is pushed away from detent groove 141 or 142.The reactionary forces 215 and 220 keep sliding detent 130 in channel121.

With the thumb lever triangular boss installed in device 100, andpositioned as shown in FIG. 6, sliding detent 130 is not free to pushaway from the detent grooves 141 or 142 in spindle 140. Reactionaryforces 225 develop that prevent such movement of sliding detent 130 dueto a moment 200. Furthermore, seat angle 133 positions the reactionaryforces 225 such that the net resulting force passes to the left of thumblever center of rotation 235. This geometry creates a moment 245 and aresulting reactionary force 240. This preferred arrangement results in amechanism that cannot be back-driven by a moment 200 without shearingtriangular boss 114. Seat angle 133 could be zero or negative. If seatangle 133 were a negative value, device 100 would then begin to rely ondetent hammer 190 to prevent triangular boss 114 from being back-driven.This is a less desirable configuration. In the preferred arrangement,the detent hammer 190 seated in detent pocket 121 or 122, must only holdthumb lever 110 (and its triangular boss 114) in place until an operatorapplies moments 101 and 102.

FIGS. 7 a,b, and c are a series of cross-sectional views that illustratethe operation of reverse mechanism 100 when moments 101 and 102 areapplied. The figures show device 100 going from a forward configuration(able to tighten a standard right-hand threaded fastener) to a reverseconfiguration (able to loosen a standard right-hand threaded fastener)at alpha=110 and then back to a forward configuration (alpha=110 throughalpha=0′).

In the FIGS. 7 a-c series, thumb lever 110 is rotated relative to cage120. The position of cage 120 and handle 160 is held fixed. Spindle 140is free to move as necessary. Cage 120 and handle 160 are held fixed inthe figures for the purpose of clearly illustrating the operation ofdevice 100. When operating device 100 with moments 101 and 102, however,cage 120 and handle 160 need not have fixed positions. They also maymove in response to applied moments 101 and 102. The handle 160 may alsohave gravitational forces or other external forces applied.

In FIG. 7 a, alpha=0, thumb lever 110 is shown at its initial position.Thumb lever 110 has been rotated counter-clockwise relative to the planeof the printed page to its fullest extent possible and detent hammer 190is fully seated in detent pocket 121. Sliding detent tooth 135 is fullyseated in detent groove 141 (device 100 could be assembled so that tooth135 is seated in groove 142 and due to symmetry the figure would lookidentical, but assume it is groove 141 for the this description). Withdetent 135 fully seated, device 100 operates as a roller clutch (citepatent here?) that transmits torque to spindle 140 when handle part 160rotates in the counter-clockwise direction relative to the printed page.High amounts of torque can be transferred through the wedging rollers150, up to the shear strength of spindle tang 141. When handle 160rotates clockwise relative to the printed page, rollers 150 in device100 do not wedge. Device 100 now functions much like a roller bearing,transmitting a small amount of torque to spindle 140. The small amountof torque transmitted is due to a combination of the lubricant viscosityand the friction that occurs between the freely sliding rollers 150 andhandle surface 162. Additional friction emanates from the surfaces ofassembled parts 120, 160, 140 and 170 as these parts rotate relative toone another.

In FIGS. 7 a and 7 b, device 100 is shown with alpha (thumb lever 110rotation angle is measured from cup pocket 121, FIG. 3) progressing inincrements from alpha=0 degrees through alpha=110 degrees. At alpha=5and alpha=10 degrees, the thumb lever 110 moves through the seat angle133 but does not perform any work to retract detent tooth 135 fromdetent groove 141. Through the first ten degrees of rotation thumb lever110 is moving out of the seat angle whose geometry provides advantageousreactionary forces 225.

Sometime shortly after alpha exceeds 10 degrees, thumb lever triangularboss radius 116 (FIG. 5) comes into contact with sliding detent holeinner surface 137 and begins performing work, retracting detent tooth135. FIG. 7 a, alpha=20 degrees through alpha=50 degrees, shows detent135 retracting from detent groove 141. As detent tooth 135 retracts,applied moments 101 and 102 cause spindle 140 to rotate relative to bothcage 120 and sliding detent 130 that is constrained in cage channel 121.Spindle 140 rotates counter-clockwise relative to the printed page andis only limited in its initial rotation by the reactionary forces thatdevelop between the detent tooth 135 and detent groove 141.

FIG. 6 a, alpha=60 is the approximate angle at which the rotation ofthumb lever 110 retracts detent tooth 135 just clear of detent groove141. Spindle 140 is now free to rotate unconstrained by detent tooth135. At this point in the operation of device 100, applied moments 101and 102 causes spindle 140 to continue counter-clockwise rotationrelative to the printed page. As spindle 140 rotates, spindle ramps 143a (FIG. 4) come into contact with rollers 150. Once in contact, ramps143 a sweep the rollers 150 counter-clockwise. As rollers 150 arerelocated in a counter-clockwise direction, they also may come intocontact with and slide along handle surface 162. Spindle 140 and rollers150 continue to rotate from applied moments 101 and 102 until rollers150 approach pillar surfaces 127 (only one surface 127 is called out inFIG. 4. There are a total of eight surfaces 127 in device 100). At thispoint rollers 150 can begin to wedge and the rotation of spindle 140 dueto applied moments 101 and 102 ends. Spindle 140 may stop rotating dueto wedging of rollers 150 or do to contact of detent tooth 136 withdetent groove 142 or both simultaneously. The magnitude of appliedmoments 101 and 102 and frictional forces determine which contact occursfirst and stops the rotation of spindle 140. In FIG. 7 b, approximatelyat or between alpha=80 and alpha=90 the rollers 150 wedge or tooth 136contacts the surface of detent groove 142, stopping rotation of spindle140.

At alpha=100, FIG. 7 b, thumb lever 110 has pushed sliding detent 130far enough down so that detent 136 is fully seated in detent groove 142.The geometry of detent teeth 135, 136 and detent grooves 141,142 areself-seating. The large mechanical advantage generated by thumb lever110 drives the detents into the matching detent grooves regardless ofapplied moment 102, once the detent has engaged the detent groove thatit mates with. When thumb lever 110 completes its 110 degree rotation(alpha=110, FIG. 7 b), device 100 is now reversed. It will now transmittorque from handle 160 to spindle 140 when the handle is rotatedclockwise relative to the printed page. This corresponds to loosening astandard right-hand threaded fastener.

FIGS. 7 b and 7 c, alpha=110 through alpha=0′, illustrate reversemechanism 100 as it operates to return to a ‘forward’ setting. To returnto a ‘forward’ setting, moments 101 and 102 must be applied in theopposite direction from their representation in FIG. 1. At the end ofthis sequence where alpha=0′, FIG. 7 c, device 100 is now back to itsoriginal configuration of alpha=0, FIG. 7 a. When device 100 moves fromalpha=110 to alpha=0′, movement of the parts is the nearly the same asthat described for the movement from alpha=0 to alpha=110. The obviousdifferences are the reversal of the rotation direction and the differentbut symmetric reaction surfaces. The symmetry of operation should beobvious by inspection.

There is a second technique by which device 100 can operate to affectthe directional setting of the wrench. It is possible to grasp device200 with a single hand such that the hand holds the handle 160 andspindle tang 141 simultaneously. Depending on the operational setting, auser may wish to or simply as habit prefer to employ this method. Inthis case, effectively the tang 141 becomes positionally fixed to thehandle 160. FIG. 8 illustrates device 100 when it operates in thisscenario, placing device 100 into a counter clockwise setting. Severalthumb lever angles (alpha=63, 65, 70, 75, 80, 90, 100, and 110) areillustrated in sectional views of device 100. The beginning thumb lever110 angles have been omitted. FIG. 8 begins with the thumb lever 110angle alpha=63. At this point in the operation of device 100, thumblever 110 has rotated from alpha=0 to alpha=63. All parts have remainedin their beginning positions except thumb lever 110 and sliding detenthammer 130 which has been retracted from detent groove 141. Atapproximately alpha=63, detent 136 has just come into contact withdetent groove 142. Once in contact, the reactionary forces that developbetween the detent 136 and detent groove 142 cause the spindle 140 torotate. The rotation is illustrated in FIG. 8, alpha=65 throughalpha=100 where the spindle rotates counter clockwise relative to theprinted page. Because of the large mechanical advantage developed bythumb lever triangle 114 and sliding detent hammer shape 137, detent 136is powerfully driven into detent groove 142 and the rotation takes placeeven if the operator holds the handle 160 and tang 141 simultaneously.Indeed, the human hand is not strong enough to prevent the rotationbecause the mechanical advantage employed by the thumb lever 110 is solarge. In FIG. 8, from alpha=100 to alpha=110, the thumb lever 110 movesthrough the seating angle 133 and the operation of device 100 iscomplete.

Cage 120 has two detent pockets 121 and 122 that are connected by detentcurve 123 (FIG. 3). FIGS. 9 a and 9 b illustrate how detent hammer 190moves along detent curve 123 as device 100 is moved back and forthbetween its forward and reverse settings. As thumb lever 110 is rotatedfrom alpha=0 through alpha=55, optional detent curve 123 forces detenthammer 190 to move towards the center of thumb lever 110's axis ofrotation. This movement causes spring 195 to compress and store energy.As thumb lever 110's rotation passes alpha=55 degrees, spring 195 beginsto release its stored energy. The reactionary forces 505 between detent190 and detent curve 123 cause thumb lever 110 to rotate through theremaining angles (alpha=60 through alpha=110, FIGS. 9 a and 9 b) underits own power.

The preferred shape of optional detent curve 123 is such that thecontact angle between detent hammer 190 and detent curve 123 is alwaysat a 45-degree angle relative to the detent hammer longitudinal axis 191(view 500, FIG. 9 b—not drawn yet) of the detent hammer 190. Theequation for this line is:r dr/dtheta=z,  Equation 3000

-   -   where r and theta are variables describing a cylindrical        coordinate system and z=1. Values other than z=1 will result in        reactionary forces that required the user to exert more or less        torque on thumb lever 110 in order to compress spring 195.

It will be appreciated by those of ordinary skill in the art that theinvention can be embodied in other specific forms without departing fromthe spirit or essential character thereof. The presently disclosedembodiments are therefore considered in all respects to be illustrativeand not restrictive. The scope of the invention is indicated by theappended claims rather than the foregoing description, and all changeswhich come within the meaning and range of equivalents thereof areintended to be embraced therein.

I claim:
 1. A roller clutch having a reversing mechanism, comprising: acase a rigid spindle disposed within said case; a cage disposed aboutsaid spindle; rigid rollers disposed about said spindle and interspersedwithin said cage; a detent slider affixed to said cage; and thumb leveraffixed to said slider.